低温连续相变萃取对蓝圆■鱼蛋白结构的影响及其抗氧化肽制备工艺优化

本文以低温连续相变萃取鱼油后的脱脂蓝圆鲹鱼粉为原料,研究了低温连续相变萃取技术对脱脂蓝圆鲹鱼粉基本成分的影响。并采用傅里叶红外光谱(FT-IR)和圆二色谱(CD)研究了该萃取技术对脱脂蓝圆鲹鱼粉中蛋白质二级结构的影响。以DPPH自由基清除率为指标,利用碱性蛋白酶酶解脱脂蓝圆鲹鱼粉制备蓝圆鲹抗氧化肽,通过正交试验进行酶解工艺优化。结果表明:脱脂蓝圆鲹鱼粉的水分含量为5.38%,灰分为4.29%,粗脂肪为0.23%,而粗蛋白高达83.78%;通过FT-IR结果可知,脱脂蓝圆鲹鱼粉中蛋白的刚性及韧性结构均没有发生明显的变化;再经过CD验证,发现脱脂蓝圆鲹鱼粉的蛋白内部保持了完整的二级结构。综上可知,低温连续相变萃取鱼油不会对脱脂蓝圆鲹鱼粉的蛋白结构和活性造成破坏;碱性蛋白酶酶解制备抗氧化肽的最佳工艺条件为:料液比1∶25 (w/v),酶解温度50℃,加酶量8000 U/g·pro,pH9.5,在此条件下测定酶解液的DPPH自由基清除率为89.99%±0.13%。

Effect of Low-temperature Continuous Phase Transition on the Structure of Decapterus maruadsi Protein and Its Optimization of Preparation Process on Antioxidant Peptides

Defatted Decapterus maruadsi powder was obtained by low-temperature continuous phase transition. The effect of low-temperature continuous phase transition on the basic components of defatted Decapterus maruadsi powder was studied. Fourier transform infrared spectroscopy(FT-IR)and circular dichroism(CD)were used to investigate the effects of this technique on the secondary structure of protein in defatted Decapterus maruadsi powder. Then alkaline protease was adopted for hydrolysis to prepare antioxidant peptides,orthogonal design was used to optimize hydrolytic condition,and the antioxidant activity of Decapterus maruadsi peptides produced by hydrolysis was measured by DPPH free radical scavenging rate. As a result,after being removed fish oil by low-temperature continuous phase transition extraction technology,the water content of the defatted Decapterus maruadsi powder was 5.38%,the ash contents was 4.29%,the crude fat was 0.23%,and the crude protein was 83.78%.The results of FT-IR showed that there was no significant change in the rigidity and toughness structure of protein in defatted Decapterus maruadsi powder. After further verification by CD,it was found that the secondary structure of protein was maintained completely in defatted Decapterus maruadsi powder. It could be concluded that the low-temperature continuous phase transition extraction technology does not destroy the structure and activity of protein in defatted Decapterus maruadsi powder. The optimal conditions of alkaline protease for hydrolysis were as follows:Ratio of water to raw material 25(mL/g),enzymatic temperature 50 ℃,enzyme dosage 8000 U/g·pro,enzymatic pH9.5. Under these conditions,the DPPH free radical clearance rate was 89.99%±0.13%,which exhibited strong antioxidant activity.